5-DOF Dynamic Modeling of Rolling Bearing with Local Defect considering Comprehensive Stiffness under Isothermal Elastohydrodynamic Lubrication

Pengfei Yan,Lixiao Wu,Kai Wang,Fengtao Wang,Changfeng Yan

doi:10.1155/2020/9310278

Abstract

The sliding of the rolling element in the load zone would cause the bearing’s wear and failure at high speed under elastohydrodynamic lubrication (EHL) condition. Aiming at this phenomenon, considering lubrication oil film, time-varying displacement, radial clearance, and comprehensive stiffness, a five degree-of-freedom (DOF) dynamic model of rolling bearing with local defect is proposed based on isothermal EHL and which is validated by experimental data. The variation of oil film stiffness, comprehensive stiffness, and vibration characteristics of rolling bearing is studied under different speeds and loads. The results show that the lubricating oils with different viscosities have a certain influence on the bearing oil film thickness and comprehensive stiffness. As the load increases, the oil film stiffness and comprehensive stiffness would increase, and the oil film thickness would decrease. And as the tangential speed increases, the oil film stiffness would increase, and the oil film thickness and comprehensive stiffness would decrease. The vibration amplitude of the rolling bearing is enhanced with the increase of the rotation speed and the radial load. This model is helpful for the optimization, the correct use of lubricants, and life prediction of rolling bearing.

Highlights

Rolling bearing is widely used to support rotating machinery due to its lower frictional resistance and higher mechanical efficiency. e presence of local defects on the surface significantly reduces the life of the rolling bearing and even affects the reliability of the device [1,2,3]. erefore, the establishment of a dynamic model of rolling bearing with local defect is helpful for the design, fault diagnosis, and life prediction of rolling bearing
Considering the changes of time-varying displacement impulse and contact stiffness, a new defect model was presented by Liu et al [9], and the effects of different defect sizes on the vibrations of the bearing were studied. en, a new dynamic model of ball bearing with local defect was proposed by Liu and Shao [10] in terms of edge topography, which was used to identify and estimate the size of defects in the bearing system by different signals
The phenomenon of local defect during a rolling element passing over the raceway surface is rarely studied under lubrication conditions. us, the purpose of this article is to reveal the comprehensive stiffness of lubrication oil film under different radial load or different velocity. e changes of stiffness under different parameters of lubrication oil film are researched, the vibration characteristics when the rolling element passes through the defect of the raceway surface during isothermal elastohydrodynamic lubrication (EHL) are explored, and the influence of the amplitude of vibration in the faulty bearing is analyzed

Summary

Introduction

Rolling bearing is widely used to support rotating machinery due to its lower frictional resistance and higher mechanical efficiency. e presence of local defects on the surface significantly reduces the life of the rolling bearing and even affects the reliability of the device [1,2,3]. erefore, the establishment of a dynamic model of rolling bearing with local defect is helpful for the design, fault diagnosis, and life prediction of rolling bearing. Liu and Shao [23] established a dynamic model to analyze the vibration response of the bearing, in which time-varying deflection excitation, time-varying contact stiffness excitation, and lubricating oil film were considered. Bizarre et al [31] calculated the force on an angular contact ball bearing with 5-DOF model, accounted for the effect of the EHL of the rolling element, and provided a comprehensive nonlinear model for evaluating the equivalent parameters of stiffness and damping under different loading conditions. E changes of stiffness under different parameters of lubrication oil film are researched, the vibration characteristics when the rolling element passes through the defect of the raceway surface during isothermal EHL are explored, and the influence of the amplitude of vibration in the faulty bearing is analyzed. It can be concluded that the changes of vibration characteristic of the rolling bearing are affected by different speeds and loads

Establishment of Dynamic Model

Mechanism of Rolling Element’s Slide

Time-Varying Displacement

Comprehensive Stiffness Affected by Oil Film

Experimental Validation

Discussion